Question

I’m retrieving a signed int from a SQL Server database and need to convert it to a “normal” looking dotted string for display to users.

Googling, I found this code:

SELECT 
   dbo.IPADDRESS.IPADDRESS,
   CAST(ROUND( (cast(dbo.IPADDRESS.IPADDRESS as bigint) / 16777216 ), 0, 1) AS varchar(4)) + '.' +
   CAST((ROUND( (cast(dbo.IPADDRESS.IPADDRESS as bigint) / 65536 ), 0, 1) % 256) AS varchar(4)) + '.' +
   CAST((ROUND( (cast(dbo.IPADDRESS.IPADDRESS as bigint) / 256 ), 0, 1) % 256) AS varchar(4)) + '.' + 
   CAST((cast(dbo.IPADDRESS.IPADDRESS as bigint) % 256 ) AS varchar(4)) as IPDottedNotation
FROM  
   dbo.IPADDRESS

which works some of the time, but produces wacky output other times. For example, converting this -1951276725 yields the result -116.-78.-30.-181.

Any suggestions? Thanks.

Answer 1

DECLARE @IPADDRESS TABLE (
  IPADDRESS INT);

INSERT INTO @IPADDRESS
VALUES      (-1139627840),
            ( 1);

SELECT 
        LTRIM(CAST(SUBSTRING(IP,4,1) AS TINYINT)) + '.' + 
        LTRIM(CAST(SUBSTRING(IP,3,1) AS TINYINT)) + '.' + 
        LTRIM(CAST(SUBSTRING(IP,2,1) AS TINYINT)) + '.' + 
        LTRIM(CAST(SUBSTRING(IP,1,1) AS TINYINT))
FROM @IPADDRESS
CROSS APPLY (SELECT CAST(IPADDRESS AS BINARY(4))) C(IP)